High speed, low power-consuming devices such as complementary metal-oxide semiconductor (CMOS) devices are highly desirable in numerous devices. Such devices include low-noise receivers and transmitters in the 10-300 GHz range used in space-based radar and communications; portable communications and RFID tags; long-endurance micro-air-vehicles (MAVs); high-efficiency, high-linearity amplifiers; and distributed autonomous sensing devices. Other devices include mixed-signal and ultra-low-power logic circuits used for A/D conversion, direct digital frequency synthesis, multiplexing, and demultiplexing.
Narrow bandgap compound semiconductors are candidates for high-frequency electronics because they exhibit high electron mobilities and peak velocities. The high velocities are reached at relatively low electric fields, enabling analog electronic devices with extremely low power consumption. For example, a Northrop-Grumman/NRL collaboration produced low-noise amplifiers (LNAs) using high-electron-mobility transistors (HEMTs) with InAs channels and AlSb barriers that operate at substantially lower power than similar circuits based upon GaAs or Si. See B. R. Bennett, R. Magno, J. B. Boos, W. Kruppa, and M. G. Ancona, Solid-State Electronics 49, 1875-1895 (2005).
Researchers at the Naval Research Laboratory are currently working to develop similar low-power technology for digital and mixed-signal circuits. For these applications, a key to low power operation is the ability to make a circuit using complementary n- and p-channel FETs (the “C” in CMOS). R. Chau, S. Datta, M. Doczy, B. Doyle, J. Jin, J. Kavalieros, A. Majumdar, M. Metz, and M. Radosavljevic, IEEE Transactions on Nanotechnology 4, 153-158 (2005). The p-FETs require heterostructures with high hole mobility and sheet density; the inverse of the product of the mobility and sheet density is the sheet resistivity.
The performance of p-FETs has been limited by high values of contact and access resistances which are a function of the sheet resistivity. In recent years, work by NRL, an Intel/QinetiQ collaboration, and SUNY-Albany used compressive strain and confinement in antimonide semiconductors to modify the band structure and achieve hole mobilities greater than 1000 cm2/V-s. Each group investigated antimonide quantum wells (QWs) on GaAs substrates and reported sheet resistivities as low as 3000-5000 Ω/□. See B. R. Bennett, M. G. Ancona, and J. B. Boos, MRS Bulletin 34, 530-536 (2009) (Bennett 2009); B. R. Bennett, M. G. Ancona, J. B. Boos, C. B. Canedy, and S. A. Khan, Journal of Crystal Growth 311, 47-53 (2008) (Bennett 2008); and B. R. Bennett, M. G. Ancona, J. Brad Boos, and B. V. Shanabrook, Applied Physics Letters 91, 042104 (2007) (Bennett 2007), each of which is hereby incorporated by reference into the present disclosure in its entirety. See also M. Radosavljevic, T. Ashley, A. Andreev, S. D. Coomber, G. Dewey, M. T. Emeny, M. Fearn, D. G. Hayes, K. P. Hilton, M. K. Hudait, R. Jefferies, T. Martin, R. Pillarisetty, W. Rachmady, T. Rakshit, S. J. Smith, M. J. Uren, D. J. Wallis, P. J. Wilding, and R. Chau, IEEE International Electron Devices Meeting 2008, Technical Digest, 727-730; and V. Tokranov, P. Nagaiah, M. Yakimov, R. J. Matyi, and S. Oktyabrsky, Journal of Crystal Growth 323, 35-38 (2011).